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参数资料
| 型号： | TC126301ECT |
| 元件分类： | 稳压器 |
| 英文描述： | 0.4 A SWITCHING REGULATOR, 115 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封装： | EIAJ, SC-74A, SOT-23A, 5 PIN |
| 文件页数： | 7/12页 |
| 文件大小： | 524K |
| 代理商： | TC126301ECT |
TC125/TC126
DS21372D-page 4
2007 Microchip Technology Inc.
3.0
DETAILED DESCRIPTION
The TC125/126 are PFM step-up DC/DC regulators for
use in systems operating from two or more cells or in
low voltage, line powered applications. Because Pulse
Frequency Modulation (PFM) is used, the TC125/126
switching frequency (and therefore supply current) is
minimized at low output loads. This is especially
important in battery operated applications (such as
pagers) that operate in Standby mode most of the
time. For example, a TC125/126 with a 3V output and
no load will consume a maximum supply current of
only 10
μA versus a supply current of 40 μA maximum
when IOUT = 30 mA. Both devices require only an
external inductor, diode and capacitor to implement a
complete DC/DC converter.
The TC125 is recommended for applications requiring
Shutdown mode as a means of reducing system supply
current. The TC125 is powered from the PS input,
which must be connected to the regulated output as
shown in Figure 3-1. PS also senses output voltage for
closed-loop regulation. Start-up current is furnished
through the inductor when input voltage is initially
applied. This action starts the oscillator, causing the
voltage at the PS input to rise, bootstrapping the
regulator into full operation.
The TC126 (Figure 3-2) is recommended for all appli-
cations not requiring Shutdown mode. It has separate
VDD and SENSE inputs, allowing it to be powered from
any source of 2.2V to 10V in the system. The VDD input
of the TC126 may be connected to the VIN, VOUT, or an
external DC voltage. Lower values of VDD result in
lower supply current, but lower efficiency due to higher
switch ON resistance. Higher VDD values increase
supply current, but drive the internal switching
transistor harder (lowering RDSON), thereby increasing
efficiency.
3.1
Low-Power Shutdown Mode
The TC125 enters a low-power Shutdown mode when
SHDN is brought low. While in shutdown, the oscillator
is disabled and the internal switch is shut off. Normal
regulator operation resumes when SHDN is brought
high. Because the TC125 uses an external diode, a
leakage path between the input voltage and the output
node (through the inductor and diode) exists while the
regulator is in shutdown. Care must be taken in system
design to assure the input supply is isolated from the
load during shutdown.
3.2
Behavior When VIN is Greater
Than the Factory-Programmed
OUT Setting
The TC125 and TC126 are designed to operate as
step-up regulators only. As such, VIN is assumed to
always be less than the factory-programmed output
voltage setting (VR). Operating the TC125/126 with
VIN > VR causes regulating action to be suspended
(and corresponding supply current reduction) until VIN
is again less than VR. While regulating action is
suspended, VIN is connected to the output voltage node
through the series combination of the inductor and
Schottky diode. Again, care must be taken to add the
appropriate isolation (MOSFET series switch or post
LDO with shutdown) during system design if this VIN/
VOUT leakage path is problematic.
FIGURE 3-1:
Typical TC125 Circuit
FIGURE 3-2:
Typical TC126 Circuit
L1
100
H Sumida CD54
D1
MA735
Shutdown
Control
1
2
3
5
4
TC125
LX
SHDN
NC
PS
GND
1.5V
ON
OFF
VOUT
3.3V @40 mA
C1
47
F/16V
Tantalum
+
1
2
3
4
5
TC126
LX
SENSE
NC
VDD
GND
3.3V
Line
Supply
L1
100
H Sumida CD54
D1
MA735
VOUT
5V @80 mA
C1
47
F/16V
Tantalum
+
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC126301ECTTR | 功能描述:开关变换器、稳压器与控制器 PFM Step-up DC/DC RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TC126303ECT | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:PFM Step-Up DC/DC Regulators |
| TC1263-2.5VAT | 功能描述:低压差稳压器 - LDO 500mA Fixed Out Adj RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| TC1263-2.5VET | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:500 mA, Fixed-Output, CMOS LDO with Shutdown |
| TC1263-2.5VETTR | 功能描述:低压差稳压器 - LDO 500mA Fixed Out Adj RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
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